This delectable and extremely choice garden species normally has pure gentian blue flowers. Occasionally the rarer form with palest lavender blue petals beautifully veined in royal blue, can be found. Now, T&M have harnessed this rarer form for you to enjoy. Its many flowers are perfectly spaced on erect spikes and a group of these really deserve a special place in the border. Flowers summer. Height 45-60cm (18-24in).

Sow late winter to mid spring in a good seed compost just covering seed with a thin layer of compost or vermiculite. Germination takes 21-30 days at 20-25C (70-75F). Sealing in a polythene bag after sowing is helpful. Place in the dark until the first seedlings appear and aim to keep the compost moist but not saturated. Lower the temperature a little after germination.

When large enough to handle, transplant to boxes or 7.5cm (3in) pots, and grow on in cooler conditions. Later, gradually acclimatise to outdoor conditions and plant out late spring after all risk of frost, 30cm (12in) apart in full sun or light shade and well drained yet moisture retentive soil.

Cut down to just above ground level in late autumn.